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This study assessed the antibiotics susceptibility of Bacillus cereus, B. thuringiensis and B. subtilis strains isolated in wells and rainwater samples in Yaounde (Cameroon). Water samples in wells were collected monthly during a long dry season (LDS), a short dry season (SDS), a long rainy season (LRS) and a short rainy season (SRS), and during the LRS and the SRS for rainwater. The antibiotics considered included Imipenem, Amikacin, Gentamycin, Ciprofloxacin, Ofloxacin, Sulfamethazol, and Tetracycline. With strains from the groundwater, the antibiotic inhibition diameters varied from 9.13 mm (Sulfametazole during SDS) to 32.78 mm (Imipenem during LDS) with B. thuringiensis, from 8.2 mm (Sulfametazole during SDS) to 35.25 mm (Imipenem during LDS) with B. cereus, and from 5.05 mm (Ofloxacin during LRS) to 29.25 mm (Imipenem during LDS) with B. subtilis. With those from the rainwater, they varied from 4.55 mm (Sulfametazole during LRS) to 25.65mm (Imipenem during LRS) with B. thuringiensis, from 2.13 mm (Imipenem during LRS) to 20.05mm (Imipenem during SRS) with B. cereus, and from 5.03 mm (Gentamicin during SRS) to 25.15mm (Tetracycline during SRS) with B. subtilis. Bacillus strains isolated during LRS were multiresistant to the majority of antibiotics. The inhibition diameters of the most antibiotics varied significantly from one season to another (p<0.05).

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Species of the genus Proteus are the cause of several infections and represent one of the microorganisms commonly involved in hospital infections. These infections are sometime difficult to treat because the antibiotic resistance phenomenon, which represents one of the greatest health challenges today. This study aimed at comparing the diversity, abundance and antimicrobial susceptibility of Proteus species isolated from hospital wastewater and Mfoundi River in Yaounde (Cameroon, Central Africa). The physicochemical parameters were measured using appropriate techniques while bacteria were isolated using standard methods and identified using the API 20E systems. The antibiogram tests were carried out using the Müller-Hinton antibiotic disc diffusion method. Antibiotics used belonged to the β-lactam, Quinolones and Aminoglycoside groups. The results obtained show that these waters are slightly alkaline (pH>7.5) and contain dissolved ions (electrical conductivity>600µS/cm; TDS>120mg/L). These waters host various Proteus species such as P. mirabilis, P. penneri and P. vulgaris, which were mostly represented in hospital wastewater. The prevalence of antimicrobial resistance varied with respect to the Proteus species and antibiotic groups. All Proteus strains were resistant to β-lactams and Quinolones. Besides, 41.8% of strains of isolated species were resistant to Gentamycin and 87.5% were sensitive to Amikacin. Most of the bacteria strains isolated in wastewater and surface water were resistant to all the antibiotics tested. Many bacterial strains tested were multi-resistant (82.76%). This multidrug resistance was more expressed in P. mirabilis and P. vulgaris species isolated from wastewater and upstream river. This represents a health risk for humans and the aquatic environment.

The health problems caused waterborne pathogens bacteria belonging to the Enterobacteriaceae family are aggravated by the rise of antimicrobial resistant bacteria phenomenon. This has been identified as one of the biggest global health challenges. The present study aims to make a comparative approach of the sensitivity/resistance to antibiotics of 4 Enterobacteriaceae Enterobacter cloacae, Citrobacter freundii, Salmonella typhi and Shigella sonnei isolated from wastewater, streams and groundwater in Yaounde town (Cameroon, Central Africa). Bacteria were isolated using standard methods their identification using the API 20E systems. The antibiogram tests were carried out using the Müller-Hinton antibiotic disc diffusion method. Results showed that inhibition diameters of antibiotic varied (P<0.05) with respect to the bacterial species on one hand, and with respect to the type of water harbored cells on the other hand. The proportion of bacterial strains of each isolated species, and which were sensitive or resistant varied from one antibiotic to another within the same antibiotics family. For β-lactams tested, no E. cloacae strain has been sensitive. The proportion of sensitive strains of other species varied between 5.88% and 23.53%. For the 2 aminoglycosides tested, 5.88% of the strains of each isolated species were resistant to gentamycin. Of the 3 quinolones tested, all strains of E. cloacae and C. freundii isolated were fully resistant to Norfloxacin and of Ofloxacin. For the 3 Sulfonamides+trimethoprim, all strains of C. freundii and S. typhi isolated were resistant to Nurofurantoin and Fosfomycin. Most of bacteria strains isolated in wastewater and surface water were resistant to all the antibiotics tested. Many bacterial strains tested were multi-resistant. This multidrug resistance was more marked in E. cloacae and C. freundii species isolated from wastewater and surface water. This represents a health risk for humans and the aquatic environment.